1. Field of the Invention
The present invention relates to a seal ring, a sealing device and a rolling bearing including the same.
2. Description of the Related Art
The inventor of the present invention newly developed a wheel speed detector for controlling the antilock brake of an automobile as shown in FIGS. 3 and 4. This detector is integrated into a sealing device 102 installed to a double-row rolling bearing 101 for wheel support. The detector detects a wheel speed using a magnetic sensor 111 and a pulsar ring 113. The sealing device 102 is comprised of the first seal ring 103 and the second seal ring 104.
The first seal ring 103 is attached to the outer ring side of the bearing 101 and constituted by attaching lips 106 and 107 to an annular body 105.
The second seal ring 104 is attached to the inner ring side of the bearing 101 and constituted by attaching lips 109 and 110 to an annular body 108.
The magnetic sensor 111 is molded on the outer periphery of the annular body 105 of the first seal ring 103 by a resin member 112. The pulsar ring 113 is bonded to the inner periphery of the annular body 108 of the second seal ring 104 at a position at which the ring 113 faces the magnetic sensor 111 in diameter direction.
The pulsar ring 113 is formed by forming rubber containing magnetic powder by vulcanization. The pulsar ring 113 is magnetized in a manner, for example, in which the polarity of the ring 113 is changed alternately in circumferential direction.
At the first stage of manufacturing the second seal ring 104, the pulsar ring 113 is bonded to the annular body 108 by vulcanization forming. At the second stage thereof, the axial lip 109 and radial lip 110, both made of rubber, are bonded to the inner side surface and the outer peripheral surface of the pulsar ring 113, respectively, by vulcanization forming.
In the above case, the lips 109 and 110 of the second seal ring 104 are provided on the inner side surface and the outer peripheral surface of the pulsar ring 113, respectively, at positions away from each other. Due to this, there is a possibility that the pulsar ring 113 is disadvantageously shifted by molten rubber inflow pressure during the vulcanization forming of the second stage. It is, therefore, difficult to control vulcanization conditions.
The main object of the present invention is, therefore, to provide a seal ring capable of preventing the positional shift of a pulsar ring in the course of vulcanization-forming lips.
The other objects of the present invention as well as features and advantages thereof will become clear from the description which follows.
In short, the present invention is a seal ring attached to a shoulder portion of a bearing ring of a rolling bearing, and comprising an annular body; a pulsar ring made of magnetized rubber, and bonded to a required position of the annular body by vulcanization forming; a first lip made of magnetized rubber, and formed integrally with the pulsar ring; and a second lip bonded to the pulsar ring by vulcanization forming.
It is preferable that the pulsar ring has different magnetic poles alternately in circumferential direction provided on an outside diameter surface of the pulsar ring.
It is preferable that the pulsar ring is formed by mixing magnetic powder with rubber, and that a content of the magnetic powder in the rubber is set to fall within a range between a lower limit of 60 mass % and an upper limit of 90 mass %.
It is preferable that the annular body includes a cylindrical portion fixed to an inner ring provided at the rolling bearing; and a disk portion directed outward in diameter direction on an axially one end portion of the cylindrical portion, that the pulsar ring is bonded to an inner surface of the disk portion, that the first lip is formed integrally with the outer peripheral surface of the pulsar ring, and that the second lip is bonded to an inner side surface of the pulsar ring.